Balanced search tree is a classical data structure. AVL tree and Red-black tree are two representative kinds of balanced tree. This is a trial to implement both of them using Java.
I use deep recursion to implement insert and delete operations in AVL tree, the core codes are only about 100 lines.
I use a class TreeVisualize.java to print tree structure in terminal, you can run AVLTreeTest.java directly to test the the AVL tree.
The delete operation in red-balck tree is kind of confusing. I use equivalent 2-3-4 tree to help comprehend those complex cases, then I find it easy to understand these cases without too much memorize.
Also, you can run RBTreeTest.java directly to test the the red-black tree. Here is a standard red-black tree visualization website https://www.cs.usfca.edu/~galles/visualization/RedBlack.html, because both our codes use predecessor replacement in delete operation, the result of our trees are theoretically the same.